Synthesis of highly stable luminescent silver nanoclusters in metal–organic framework for heightened antibacterial activity

Size of the nanoparticles plays a very crucial role in their bactericidal activity as smaller size render better perforation via bacterial cell wall and are thus found to be more effective against resistant bacterial infections also. In this regard, fluorescent silver nanoclusters (Ag NCs) having a size less than 2 nm ought to be a potent bactericidal agent against both Gram positive and Gram negative bacterial strains. However, stabilization of such small sized NPs in aqueous medium that is amenable for biological applications is very challenging. Herein, a simple and fast method of synthesis of Ag NCs was proposed using metal–organic framework (MOFs) as scaffold, which was found to be very stable in the ambient conditions. As-synthesized Ag NCs-in-MOF nanocomposite was characterized by UV–Vis spectroscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The nanocomposite was highly bactericidal against both Gram positive and Gram negative bacterial strains and caused cell wall perforation that was evident from flow cytometry analysis. Results also showed that DNA damage had occurred due to treatment of Ag NCs-in-MOF, ultimately leading to bacterial cell death with considerably lower dose of silver.